Currently, efforts to make energetic materials insensitive have been a significant issue in development of explosives and a propellant. As a part of such efforts, plastic bonded explosives (PBXs) having low sensitivity and improved mechanical properties while maintaining high energy properties have been developed. Such PBX now becomes an elementary component of high-energy explosives, polymeric binders and other additives used in a small amount such as a plasticizer or a stabilizer.
Currently, a polyurethane polymeric binder on the basis of a hydroxyl-terminated polybutadiene (HTPB) has been used as a widely applicable polymeric binder system, together with various additives so as to improve processability, mechanical properties and chemical stability. Although such polymeric binder shows excellent properties in making high-energy materials insensitive, it has been proposed that it generally disadvantageously reduces the energy density of PBX on the whole owing to its low energy potential. In this regard, many studies have been being made to increase the whole energy density through development of energetic binders and plasticizers containing energetic functional groups such as, for example, nitro (C—NO2), nitrate (O—NO2), nitramine (N—NO2), azido (—N3) and difluoroamino (—NF2) and application thereof.
The term “energetic functional groups” as used herein has common and general meaning as used in the field of molecular explosives, i.e., referring to functional groups, when being applied to a molecular explosive or a plasticizer, known to contribute to the increase in the whole energy level of PBX to which the explosive or plasticizer were applied. Nitro (C—NO2), nitrate (O—NO2), nitramine (N—NO2), azido (—N3), difluoroamino (—NF2) or the like as described above may be mentioned. The term “energetic” as used herein means that the whole energy level of a molecular explosive is more increased by any known methods comprising the introduction of such “energetic” functional groups.
However, those polymeric binders and plasticizers which comprise such energetic functional groups have problems such as low heat stability, non-compatibility with explosives and low processability. Therefore, it has been an important rising issue to ultimately achieve both high performance and insensitiveness in explosives. Further, when an energetic plasticizer is applied, an additional problem such as a migration of the energetic plasticizer from PBX occurs over a long period of time. Such migration of an energetic plasticizer involves further additional problems in PBX such as increase in sensitivity to impact and decrease in storage stability and long-term stability owing to deterioration in mechanical properties. Therefore, the realization of an explosive having both high performance and insensitiveness still has been an important matter to be achieved in this field of art.
When a highly energetic polymer which can satisfy both high performance and insensitiveness at the same time is prepared, it is anticipated to obtain a novel energy material which is combined with a molecular explosive and a binder and has an excellent performance and safety.